This invention relates in general to vehicle disc brake assemblies and in particular to an improved structure for a parking and emergency brake mechanism adapted for use in such a vehicle disc brake assembly.
Most vehicles are equipped with a brake system for slowing or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art.
A typical disc brake assembly includes a brake rotor which is secured to the wheel of the vehicle for rotation therewith. The brake rotor includes a pair of opposed friction surfaces which are selectively engaged by portions of a caliper assembly. The caliper assembly is slidably supported by pins secured to an anchor plate. The anchor plate is secured to a non-rotatable component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake shoes which are disposed on opposite sides of the rotor. The brake shoes are operatively connected to one or more hydraulically actuated pistons for movement between a non-braking position, wherein they are spaced apart from the opposed friction surfaces of the brake rotor, and a braking position, wherein they are moved into frictional engagement with the opposed friction surfaces of the brake rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake shoes from the non-braking position to the braking position so as to frictionally engage the friction surfaces of the brake rotor and thereby slow or stop the rotation of the associated wheel of the vehicle.
When a disc brake assembly is used for the rear wheels of the vehicle, a mechanically actuated parking and emergency brake mechanism is also usually provided for selectively actuating the disc brake assembly. The parking and emergency brake mechanism is applied by a cable through foot or hand application by the vehicle operator. The parking and emergency brake mechanism is typically either a "drum-in-hat" type of parking and emergency brake, such as shown in U.S. Pat. No. 5,180,037 to Evans, or an "integral" type of parking and emergency brake, such as shown in U.S. Pat. No. 5,038,895 to Evans.